Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF INVENTION
SPUN STAPLE YARNS MADE FROM BLENDS OF RIGID-ROD FIBERS
AND FIBERS DERIVED FROM DIAMINO DIPHENYL SULFONE AND
FABRICS AND GARMENTS MADE THEREFROM AND METHODS FOR
MAKING SAME
FIELD OF THE INVENTION
The invention relates to a spun staple yarns, and fabrics and garments
comprising these yarns, and methods of making the same. The yams have 20 to 50
parts by weight of a polymeric staple fiber containing a structure derived
from a
monomer selected from the group consisting of 4,4'diaminodiphenyl sulfone,
3,3'diaminodiphenyl sulfone, and mixtures thereof; and 50 to 80 parts by
weight
of rigid-rod staple fiber based on 100 parts by weight of the polymeric fiber
and
the rigid-rod fiber in the yarn.
BACKGROUND OF THE INVENTION
Firefighters, emergency response personnel, members of the military,
racing personnel, and industrial workers that can be exposed to flames, high
temperatures, and/or electrical arcs and the like, need protective clothing
and
articles made from thermally resistant fabrics. Any increase in the
effectiveness of
these protective articles, or any increase in the comfort or durability of
these
articles while maintaining protection performance, is welcomed.
Rigid-rod para-aramid and polyazole fiber has good low thermal shrinkage
when exposed to high heat flux or flame and therefore is desired for
protective
apparel. Unfortunately, such rigid-rod fibers fibrillate easily upon abrasion.
Their
highly-ordered rigid-rod structure has a propensity for fibrillation
attributable to
the lack of lateral forces between macromolecules. As the content of such
fibers
in a fabric increases above 5 weight percent, the extent of potential
fibrillation of
the fibers also increases and actual fibril formation can become more
noticeable
and objectionable. Therefore what is desired is to reduce the fibrillation of
fabrics
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and apparel containing such rigid rod fibers without adversely affecting the
ability
of the protective apparel to protect the wearer.
A fiber known as polysulfonamide fiber (PSA) is made from a poly
(sulfone-amide) polymer and has good thermal resistance due to its aromatic
content and also has low modulus, which imparts more flexibility (i.e.
comfort) to
fabrics made from the fiber; however, the fiber has low tensile break
strength.
This low tensile strength in fibers has a major impact on the mechanical
properties
of fabrics made from these fibers. PSA, however, does not readily fibrillate
so
there is a desire to utilize this comfortable fiber in protective apparel that
can be
affected by abrasive environments, especially in applications such as
firefighters'
turnout coats that must function in extreme environments.
SUMMARY OF THE INVENTION
In some embodiments, this invention relates to a spun yarn, woven fabric,
and protective garment, comprising 20 to 50 parts by weight of a polymeric
staple
fiber containing a polymer or copolymer derived from a monomer selected from
the group consisting of 4,4'diaminodiphenyl sulfone, 3,3'diaminodiphenyl
sulfone, and mixtures thereof; and 50 to 80 parts by weight of a rigid-rod
staple
fiber, based on 100 parts by weight of the polymeric fiber and the rigid-rod
fiber
in the yarn. This invention also relates to a flame-resistant garment
comprising in
order, an inner thennal lining, a liquid barrier, and an outer shell fabric
made from
a fabric containing the spun yam.
In some other embodiments, this invention relates to a method of
producing a flame-resistant spun yarn comprising forming a fiber mixture of 20
to
50 parts by weight of a polymeric staple fiber containing a polymer or
copolymer
derived from a monomer selected from the group consisting of
4,4'diaminodiphenyl sulfone, 3,3'diaminodiphenyl sulfone, and mixtures
thereof;
and 50 to 80 parts by weight of a rigid-rod staple fiber, based on 100 parts
by
weight of the polymeric fiber and the rigid-rod fiber in the yarn; and
spinning the
fiber mixture into a spun staple yarn.
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DETAILED DESCRIPTION
The invention concerns a spun staple yarn made from a polymeric staple
fiber derived diamino diphenyl sulfone monomer and a rigid-rod staple fiber.
In
some embodiments the rigid-rod staple fiber has a tensile modulus of 200 grams
per denier (180 grams per dtex) or greater. In some embodiments the staple
yarn
is flame resistant. By "flame resistant" it is meant the spun staple yarn, or
fabrics
made from the yarn, will not support a flame in air. In preferred embodiments
the
fabrics have a limiting oxygen index (LOI) of 26 and higher.
For purposes herein, "rigid-rod fiber" means fibers made from rigid-rod
aromatic polymers having what are known in the art as rigid spacer segments;
these rigid-rod fibers also form fibrils with abrasion or wear. The rigid
spacers
often contain another cyclic unit, or functional end groups such as -NH-, -CO-
, -
O-, -COO-, -N=N-, and/or -CH=CH-. Generally these rigid-rod polymers have
highly para-oriented aromatic groups and the fibers made from these polymers
have a high tensile modulus. With wear or abrasion, rigid-rod fibers readily
fibrillate; that is, they form structures having a central fiber stalk with
fibrils
extending therefrom. The stalk is generally columnar and 4 to 50 microns in
diameter and the fibrils are hair-like members only a fraction of a micron or
a few
microns in diameter attached to the stalk and are 10 to 100 microns long.
For purposes herein, the term "fiber" is defined as a flexible,
macroscopically homogeneous body having a high ratio of length to the width of
the cross-sectional area perpendicular to that length. The fiber cross section
can
be any shape, but is typically round. Herein, the term "filament" or
"continuous
filament" is used interchangeably with the term "fiber."
As used herein, the term "staple fibers" refers to fibers that are cut to a
desired length or are stretch broken, or fibers that occur naturally with or
are made
having a low ratio of length to the width of the cross-sectional area
perpendicular
to that length when compared with filaments. Man made staple fibers are cut or
made to a length suitable for processing on cotton, woolen, or worsted yarn
spinning equipment. The staple fibers can have (a) substantially uniform
length,
(b) variable or random length, or (c) subsets of the staple fibers have
substantially
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uniform length and the staple fibers in the other subsets have different
lengths,
with the staple fibers in the subsets mixed together forming a substantially
uniform distribution.
In some embodiments, suitable staple fibers have a length of 0.25
centimeters (0.1 inches) to 30 centimeters (12 inches). In some embodiments,
the
length of a staple fiber is from 1 cm (0.39 in) to 20 cm (8 in). In some
preferred
embodiments the staple fibers made by short staple processes have a staple
fiber
length of 1 cm (0.39 in) to 6 cm (2.4 in).
The staple fibers can be made by any process. For example, the staple
fibers can be cut from continuous straight fibers using a rotary cutter or a
guillotine cutter resulting in straight (i.e., non crimped) staple fiber, or
additionally cut from crimped continuous fibers having a saw tooth shaped
crimp
along the length of the staple fiber, with a crimp (or repeating bend)
frequency of
preferably no more than 8 crimps per centimeter.
The staple fibers can also be formed by stretch breaking continuous fibers
resulting in staple fibers with deformed sections that act as crimps. Stretch
broken
staple fibers can be made by breaking a tow or a bundle of continuous
filaments
during a stretch break operation having one or more break zones that are a
prescribed distance creating a random variable mass of fibers having an
average
cut length controlled by break zone adjustment.
Spun staple yarn can be made from staple fibers using traditional long and
short staple ring spinning processes that are well known in the art. For short
staple, cotton system spinning fiber lengths from 1.9 to 5.7 cm (0.75 in to
2.25 in)
are typically used. For long staple, worsted or woolen system spinning, fibers
up
to 16.5 cm (6.5 in) are typically used. However, this is not intended to be
limiting
to ring spinning because the yarns may also be spun using air jet spinning,
open
end spinning, and many other types of spinning which converts staple fiber
into
useable yarns.
Spun staple yarns can also be made directly by stretch breaking using
stretch-broken tow to top staple processes. The staple fibers in the yarns
formed
by traditional stretch break processes typically have length of up to 18 cm (7
in)
long. However spun staple yarns made by stretch breaking can also have staple
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fibers having maximum lengths of up to around 50 cm (20 in.) through processes
as described for example in PCT Patent Application No. WO 0077283. Stretch
broken staple fibers normally do not require crimp because the stretch-
breaking
process imparts a degree of crimp into the fiber.
The term continuous filament refers to a flexible fiber having relatively
small-diameter and whose length is longer than those indicated for staple
fibers.
Continuous filament fibers and multifilament yams of continuous filaments can
be
made by processes well known to those skilled in the art.
By polymeric fibers containing a polymer or copolymer derived from an
amine monomer selected from the group consisting of 4,4'diaminodiphenyl
sulfone, 3,3'diaminodiphenyl sulfone, and mixtures thereof, it is meant the
polymer fibers were made from a monomer generally having the structure:
NHz-Ar]-SOz-Arz-NHz
wherein Arl and Arz are any unsubstituted or substituted six-membered aromatic
group of carbon atoms and Arl and Ar2 can be the same or different. In some
preferred embodiments Arl and Ar2 are the same. Still more preferably, the six-
membered aromatic group of carbon atoms has meta- orpara-oriented linkages
versus the SOz group. This monomer or multiple monomers having this general
structure are reacted with an acid monomer in a compatible solvent to create a
polymer. Useful acids monomers generally have the structure of
Cl-CO-Ar3-CO-Cl
wherein Ar3 is any unsubstituted or substituted aromatic ring structure and
can be
the same or different from Arl and/or Ar2. In some preferred embodiments Ar3
is
a six-membered aromatic group of carbon atoms. Still more preferably, the six-
membered aromatic group of carbon atoms has meta- orpara-oriented linkages.
In some preferred embodiments Arl and Ar2 are the same and Ar3 is different
from both Arl and Ar2. For example, Arl and Ar2 can be both benzene rings
having meta-oriented linkages while Ar3 can be a benzene ring having para-
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oriented linkages. Examples of useful monomers include terephthaloyl chloride,
isophthaloyl chloride, and the like. In some preferred embodiments, the acid
is
terephthaloyl chloride or its mixture with isophthaloyl chloride and the amine
monomer is 4,4'diaminodiphenyl sulfone. In some other preferred embodiments,
the amine monomer is a mixture of 4,4'diaminodiphenyl sulfone and
3,3'diaminodiphenyl sulfone in a weight ratio of 3:1, which creates a fiber
made
from a copolymer having both sulfone monomers.
In still another preferred embodiment, the polymeric fibers contain a
copolymer, the copolymer having both repeat units derived from sulfone amine
monomer and an amine monomer derived from paraphenylene diamine and/or
metaphenylene diamine. In some preferred embodiments the sulfone amide repeat
units are present in a weight ratio of 3:1 to other amide repeat units. In
some
embodiments, at least 80 mole percent of the amine monomers is a sulfone amine
monomer or a mixture of sulfone amine monomers. For convenience, herein the
abbreviation "PSA" will be used to represent all of the entire classes of
fibers
made with polymer or copolymer derived from sulfone monomers as previously
described.
In one embodiment, the polymer and copolymer derived from a sulfone
monomer can preferably be made via polycondensation of one or more types of
diamine monomer with one or more types of chloride monomers in a dialkyl
amide solvent suchs as N-methyl pyrrolidone, dimethyl acetamide, or mixtures
thereof. In some embodiments of the polymerizations of this type an inorganic
salt
such as lithium chloride or calcium chloride is also present. If desired the
polymer
can be isolated by precipitation with non-solvent such as water, neutralized,
washed, and dried. The polymer can also be made via interfacial polymerization
which produces polymer powder directly that can then be dissolved in a solvent
for fiber production.
The polymer or copolymer can be spun into fibers via solution spinning,
using a solution of the polymer or copolymer in either the polymerization
solvent
or another solvent for the polymer or copolymer. Fiber spinning can be
accomplished through a multi-hole spinneret by dry spinning, wet spinning, or
dry-jet wet spinning (also known as air-gap spinning) to create a multi-
filament
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yarn or tow as is known in the art. The fibers in the multi-filament yarn or
tow
after spinning can then be treated to neutralize, wash, dry, or heat treat the
fibers
as needed using conventional technique to make stable and useful fibers.
Exemplary dry, wet, and dry-jet wet spinning processes are disclosed U.S.
Patent
Nos. 3,063,966; 3,227,793; 3,287,324; 3,414,645; 3,869,430; 3,869,429;
3,767,756; and 5,667,743.
Specific methods of making PSA fibers or copolymers containing sulfone
amine monomers are disclosed in Chinese Patent Publication 1389604A to Wang
et al. This reference discloses a fiber known as polysulfonamide fiber (PSA)
made
by spinning a copolymer solution formed from a mixture of 20 to 50 weight
percent 4,4'diaminodiphenyl sulfone and 50 to 80 weight percent
3,3'diaminodiphenyl sulfone copolymerized with equimolar amounts of
terephthaloyl chloride in dimethylacetamide. Chinese Patent Publication
1631941 A to Chen et al. also discloses a method of preparing a PSA copolymer
spinning solution formed from a mixture of 4,4'diaminodiphenyl sulfone and
3,3'diaminodiphenyl sulfone in a mass ratio of from 10:90 to 90:10
copolymerized with equimolar amounts of terephthaloyl chloride in
dimethylacetamide. Still another method of producing copolymers is disclosed
in
United States Patent No. 4,169,932 to Sokolov et al. This reference discloses
preparation of poly(paraphenylene) terephthalamide (PPD-T) copolymers using
tertiary amines to increase the rate of polycondensation. This patent also
discloses
the PPD-T copolymer can be made by replacing 50 to 80 mole percent of the
paraphenylene diamine (PPD) by another aromatic diamine such as
4,4'diaminodiphenyl sulfone.
In some embodiments, the spun staple yams can also include a rigid-rod
staple fiber having a limiting oxygen index (LOI) of 21 or greater, meaning
the
rigid-rod staple fiber or fabrics made solely from the rigid-rod staple fiber
will not
support a flame in air. In some preferred embodiments the rigid-rod staple
fiber
has a LOI of at least 26 or greater.
In some preferred embodiments the rigid-rod staple fiber has a break
tenacity greater than the break tenacity of the PSA staple fiber, which is
generally
3 grams per denier (2.7 grams per dtex). In some embodiments, the rigid-rod
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staple fiber has a break tenacity of at least 5 grams per denier (4.5 grams
per dtex)
or greater. In some other embodiments the rigid-rod staple fiber has a break
tenacity of at least 10 grams per denier (9 grams per dtex) or greater. The
addition of the higher tenacity rigid-rod staple fiber provides the spun yarn
with
additional strength that translates into improved strength and durability in
the final
fabrics and garments made from the spun yarns. Also, in some cases, it is
believed
the additional tenacity provided by the rigid-rod staple fiber to the spun
yarn is
magnified in the fabrics and garments made from the yam, resulting in more
tenacity improvement in the fabric than in the spun yarn.
Different fibers can be used as the rigid-rod staple fiber. In some
embodiments para-aramid fiber can be used in the blend as the rigid-rod staple
fiber. By "aramid" is meant a polyamide wherein at least 85% of the amide (-
CONH-) linkages are attached directly to two aromatic rings. Additives can be
used with the aramid and, in fact, it has been found that up to as much as 10
percent, by weight, of other polymeric material can be blended with the aramid
or
that copolymers can be used having as much as 10 percent of other diamine
substituted for the diamine of the aramid or as much as 10 percent of other
diacid
chloride substituted for the diacid chloride of the aramid. In some
embodiments,
the preferred para-aramid is poly(paraphenylene terephthalamide). Methods for
making para-aramid fibers useful are generally disclosed in, for example,
United
States Patent Nos. 3,869,430; 3,869,429; and 3,767,756. Various forms of such
aromatic polyamide organic fibers are sold under the trademarks of Kevlar and
Twaron by respectively, E. I. du Pont de Nemours and Company, of
Wilmington, Delaware; and Teijin, Ltd, of Japan. Also, fibers based on
copoly(p-
phenylene/3,4'-diphenyl ether terephthalamide) are defined as para-aramid
fibers
as used herein. One commercially available version of these fibers is known as
Technora fiber also available from Teijin, Ltd.
In some embodiments polyazole fibers can be used as the rigid-rod fiber in
the blend. For example, suitable polyazoles include polybenzazoles,
polypyridazoles, and the like, and can be homopolymers or copolymers.
Additives can be used with the polyazoles and up to as much as 10 percent, by
weight, of other polymeric material can be blended with the polyazoles. Also
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copolymers can be used having as much as 10 percent or more of other monomer
substituted for a monomer of the polyazoles. Suitable polyazole homopolymers
and copolymers can be made by known procedures, such as those described in
U.S. Patents 4,533,693 (to Wolfe, et al., on Aug. 6, 1985), 4,703,103 (to
Wolfe, et
al., on Oct. 27, 1987), 5,089,591 (to Gregory, et al., on Feb. 18, 1992),
4,772,678
(Sybert, et al., on Sept. 20, 1988), 4,847,350 (to Harris, et al., on Aug. 11,
1992),
and 5,276,128 (to Rosenberg, et al., on Jan. 4, 1994).
In some embodiments the preferred polybenzazoles are
polybenzimidazoles, polybenzothiazoles, and polybenzoxazoles. If the
polybenzazole is a polybenzimidazole, preferably it is poly[5,5'-bi-1H-
benzimidazole]-2,2'-diyl-1,3-phenylene which is called PBI. If the
polybenzazole
is a polybenzothiazole, preferably it is a polybenzobisthiazole and more
preferably it is poly(benzo [ 1,2-d:4,5-d']bisthiazole-2,6-diyl- 1,4-phenylene
which
is called PBT. If the polybenzazole is a polybenzoxazole, preferably it is a
polybenzobisoxazole and more preferably it is poly(benzo[ 1,2-d:4,5-
d']bisoxazole-2,6-diyl-1,4-phenylene which is called PBO. In some embodiments
the preferred polypyridazoles are rigid rod polypyridobisazoles including
poly(pyridobisimidazole), poly(pyridobisthiazole), and poly(pyridobisozazole).
The preferred poly(pyridobisozazole) is poly(1,4-(2,5-dihydroxy)phenylene-2,6-
pyrido[2,3-d:5,6-d']bisimidazole which is called PIPD. Suitable
polypyridobisazoles can be made by known procedures, such as those described
in
U.S. Patent 5,674,969.
In some embodiments, this invention relates to a flame-resistant spun yam,
woven fabric, and protective garment, comprising 20 to 50 parts by weight of a
polymeric staple fiber containing a structure derived from a monomer selected
from the group consisting of 4,4'diaminodiphenyl sulfone, 3,3'diaminodiphenyl
sulfone, and mixtures thereof, and 50 to 80 parts by weight of a rigid-rod
staple
fiber, based on the total amount of the polymeric fiber and the rigid-rod
fiber in
the yarn. In some embodiments the rigid-rod fiber has a tensile modulus of 200
grams per denier (180 grams per dtex) or greater and a tenacity of 10 grams
per
denier (9 grams per dtex) or greater. In some preferred embodiments the
polymeric staple fiber is present in an amount of 20 to 35 parts by weight,
and the
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rigid-rod staple fiber is present in an amount of 65 to 80 parts by weight,
based on
the total amount (100 total parts) of the polymeric staple fiber and the rigid-
rod
staple fiber in the yam.
In some preferred embodiments the various types of staple fibers are
present as a staple fiber blend. By fiber blend it is meant the combination of
two
or more staple fiber types in any manner. Preferably the staple fiber blend is
an
"intimate blend", meaning the various staple fibers in the blend form a
relatively
uniform mixture of the fibers. In some embodiments the two or more staple
fiber
types are blended prior to or while the yarn is being spun so that the various
staple
fibers are distributed homogeneously in the staple yarn bundle.
If desired, the staple fiber blend can have, in addition, 1 to 5 parts by
weight of an antistatic fiber that reduces the propensity for static buildup
in the
staple yams, fabric, and garements. In some preferred embodiments the fiber
for
imparting this antistatic property is a sheath-core staple fiber having a
nylon
sheath and a carbon core. Suitable materials for supplying antistatic
properties are
described in United States Patent Nos. 3,803,453 and 4,612,150.
The polymeric or PSA staple fiber while being fire retardant is a very
weak fiber, with fibers generally having break tenacity of 3 grams per denier
(2.7
grams per dtex) and low tensile moduli of 30 to 60 grams per denier (27 to 55
grams per dtex). It is believed that the use of as little as 20 percent by
weight PSA
staple fiber in combination with the rigid-rod staple fiber can not only
contribute
to increased fabric comfort but can also reduce the propensity for the yarns
to
fibrillate. A garment fabric made from this combination of staple fibers has
lower
stiffness and therefore is more flexible than a garment fabric made totally
from
higher amounts of the higher modulus rigid-rod staple fiber and has better
abrasion performance in extreme environments.
Fabrics can be made from the spun staple yarns and can include, but is not
limited to, woven or knitted fabrics. General fabric designs and constructions
are
well known to those skilled in the art. By "woven" fabric is meant a fabric
usually
formed on a loom by interlacing warp or lengthwise yarns and filling or
crosswise
yams with each other to generate any fabric weave, such as plain weave,
crowfoot
weave, basket weave, satin weave, twill weave, and the like. Plain and twill
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weaves are believed to be the most common weaves used in the trade and are
preferred in many embodiments.
By "knitted" fabric is meant a fabric usually formed by interlooping yarn
loops by the use of needles. In many instances, to make a knitted fabric spun
staple yarn is fed to a knitting machine which converts the yarn to fabric. If
desired, multiple ends or yarns can be supplied to the knitting machine either
plied
of unplied; that is, a bundle of yarns or a bundle of plied yarns can be co-
fed to
the knitting machine and knitted into a fabric, or directly into a article of
apparel
such as a glove, using conventional techniques. In some embodiments it is
desirable to add functionality to the knitted fabric by co-feeding one or more
other
staple or continuous filament yarns with one or more spun staple yarns having
the
intimate blend of fibers. The tightness of the knit can be adjusted to meet
any
specific need. A very effective combination of properties for protective
apparel
has been found in for example, single jersey knit and terry knit patterns.
In some particularly useful embodiments, the spun staple yarns can be
used to make flame-resistant garments. In some embodiments the garments can
have essentially one layer of the protective fabric made from the spun staple
yarn.
Garments of this type include jumpsuits and coveralls for fire fighters or for
military personnel. Such suits are typically used over the firefighters'
clothing and
can be used to parachute into an area to fight a forest fire. Other gannents
can
include pants, shirts, gloves, sleeves and the like that can be worn in
situations
such as chemical processing industries or industrial electricaUutility where
an
extreme thermal event might occur. In some preferred embodiments the fabrics
have an arc resistance of at least 0.8 calories per square centimeter per
ounce per
square yard.
In other embodiments the spun staple yarn is used to make a multi-layer
flame-resistant gannent. One such garment has a general construction such as
disclosed in United States Patent No. 5,468,537. Such garments generally have
three layers or three types of fabric constructions, each layer or fabric
construction
performing a distinct function. There is an outer shell fabric that provides
flame
protection and serves as a primary defense from flames for the fire fighter,
and in
most embodiments this is the layer that uses the spun staple yarn. Adjacent
the
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outer shell is a moisture barrier that is typically a liquid barrier but can
be selected
such that it allows moisture vapor to past through the barrier. Laminates of
Gore-
Tex PTFE membrane or Neoprene membranes on a fibrous nonwoven or
woven meta-aramid scrim fabric are moisture barriers typically used in such
constructions. Adjacent the moisture barrier is a thermal liner, which
generally
includes a batt of heat resistant fiber attached to an internal face cloth.
The
moisture barrier keeps the thermal liner dry and thermal liner protects the
wearer
from heat stress from the fire or heat threat being addressed by the wearer.
In another embodiment, this invention relates to a method of producing a
flame-resistant spun yarn comprising forming a fiber mixture of 20 to 50 parts
by
weight of a polymeric staple fiber containing a structure derived from a
monomer
selected from the group consisting of 4,4'diaminodiphenyl sulfone,
3,3'diaminodiphenyl sulfone, and mixtures thereof; and 50 to 80 parts by
weight
of a rigid-rod staple fiber, based on the total amount (100 total parts) of
the
polymeric fiber and the rigid-rod fiber in the yarn; and spinning the fiber
mixture
into a spun staple yarn. In some embodiments, the rigid-rod fiber has a
tensile
modulus of 200 grams per denier (180 grams per dtex) or greater. In some
preferred embodiments the polymeric staple fiber is present in an amount of 20
to
35 parts by weight, and the rigid-rod staple fiber is present in an amount of
65 to
80 parts by weight, based on the total amount of the polymeric staple fiber
and the
rigid-rod staple fiber in the yarn.
In one embodiment the fiber mixture of the polymeric staple fiber and the
rigid-rod staple fiber is formed by making an intimate blend of the fibers. If
desired, other staple fibers can be combined in this relatively uniform
mixture of
staple fibers. The blending can be achieved by any number of ways known in the
art, including processes that creel a number of bobbins of continuous
filaments
and concurrently cut the two or more types of filaments to form a blend of cut
staple fibers; or processes that involve opening bales of different staple
fibers and
then opening and blending the various fibers in openers, blenders, and cards;
or
processes that form slivers of various staple fibers which are then further
processed to form a mixture, such as in a card to form a sliver of a mixture
of
fibers. Other processes of making an intimate fiber blend are possible as long
as
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the various types of different fibers are relatively uniformly distributed
throughout
the blend. If yams are formed from the blend, the yams have a relatively
uniform
mixture of the staple fibers also. Generally, in most preferred embodiments
the
individual staple fibers are opened or separated to a degree that is normal in
fiber
processing to make a useful fabric, such that fiber knots or slubs and other
major
defects due to poor opening of the staple fibers are not present in an amount
that
detract from the final fabric quality.
In a preferred process, the intimate staple fiber blend is made by first
mixing together staple fibers obtained from opened bales, along with any other
staple fibers, if desired for additional functionality. The fiber blend is
then
formed into a sliver using a carding machine. A carding machine is commonly
used in the fiber industry to separate, align, and deliver fibers into a
continuous
strand of loosely assembled fibers without substantial twist, commonly known
as
carded sliver. The carded sliver is processed into drawn sliver, typically by,
but
not limited to, a two-step drawing process.
Spun staple yams are then formed from the drawn sliver using techniques
including conventional cotton system or short-staple spinning processes such
as
open-end spinning and ring-spinning; or higher speed air spinning techniques
such
as Murata air-jet spinning where air is used to twist the staple fibers into a
yam.
The formation of spun yams can also be achieved by use of conventional woolen
system or long-staple processes such as worsted or semi-worsted ring-spinning
or
stretch-break spinning. Regardless of the processing system, ring-spinning is
the
generally preferred method for making the spun staple yams.
TEST METHODS
Basis weight values were obtained according to FTMS 191A; 5041.
Abrasion Test. The abrasion performance of fabrics is determined in
accordance with ASTM D-3884-01 "Standard Guide for Abrasion Resistance of
Textile Fabrics (Rotary Platform, Double Head Method)".
Instrumented Thermal Manikin Test. Bum protection performance iss
determined using "Predicted Bum Injuries for a Person Wearing a Specific
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Garment or System in a Simulated Flash Fire of Specific Intensity" in
accordance
with ASTM F 1930 Method (1999) using an instrumented thermal mannequin
with standard pattern coverall made with the test fabric.
Arc Resistance Test. The arc resistance of fabrics is determined in
accordance with ASTM F-1959-99 "Standard Test Method for Determining the
Arc Thermal Performance Value of Materials for Clothing". The Arc Thermal
Performance Value (ATPV) of each fabric, which is a measure of the amount of
energy that a person wearing that fabric could be exposed to that would be
equivalent to a 2nd degree burn from such exposure 50% of the time.
Grab Test. The grab resistance of fabrics (the break tensile strength) is
determined in accordance with ASTM D-5034-95 "Standard Test Method for
Breaking Strength and Elongation of Fabrics (Grab Test)".
Tear Test. The tear resistance of fabrics is determined in accordance with
ASTM D-5587-03 "Standard Test Method for Tearing of Fabrics by Trapezoid
Procedure".
Thermal Protection Performance (TPP) Test. The thermal protection
performance of fabrics is determined in accordance with NFPA 2112 "Standard
on Flame Resistant Garments for Protection of Industrial Personnel Against
Flash
Fire". The thermal protective performance relates to a fabric's ability to
provide
continuous and reliable protection to a wearer's skin beneath a fabric when
the
fabric is exposed to a direct flame or radiant heat.
Vertical Flame Test. The char length of fabrics is determined in
accordance with ASTM D-6413-99 "Standard Test Method for Flame Resistance
of Textiles (Vertical Method)".
Limiting Oxygen Index (LOI) is the minimum concentration of oxygen,
expressed as a volume percent, in a mixture of oxygen and nitrogen that will
just
support the flaming combustion of a material initially at room temperature
under
the conditions of ASTM G125 / D2863.
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Examples
The invention is illustrated by, but is not intended to be limited by the
following examples. All parts and percentages are by weight unless otherwise
indicated.
Example 1
This example illustrates flame-resistant spun yarns and fabrics of intimate
blends of PSA fiber and rigid-rod para-aramid staple fiber. The PSA staple
fiber is
made from polymer made from 4,4'diaminodiphenyl sulfone and
3,3'diaminodiphenyl sulfone copolymerized with equimolar amounts of
terephthaloyl chloride in dimethylacetamide and is known under the common
designation of Tanlon ; the para-aramid staple fiber is made from
poly(paraphenylene terephthalamide) polymer, has a modulus of 500 grams per
denier (450 grams per dtex) and a tenacity of 23 grams per denier (21 grams
per
dtex), and is marketed by E. I. du Pont de Nemours & Company under the
trademark Kevlar 29 fiber.
A picker blend sliver of 60 wt.% para-aramid fiber and 40% PSA fiber is
prepared and processed by the conventional cotton system equipment and is then
spun into a staple yarn having a twist multiplier 4.0 and a single yarn size
of 21
tex (28 cotton count) using a ring spinning frame. Two such single yarns are
then
plied on a plying machine to make a two-ply flame resistant yarn for use as a
fabric warp yam. Using a similar process and the same twist and blend ratio, a
24
tex (24 cotton count) singles yarn is made and two of these single yarns are
plied
to form a two-ply fabric fill yarn.
The ring spun yarns of intimate blends of PSA fiber and
poly(paraphenylene terephthalamide) staple fiber are then used as the warp and
fill yarns and are woven into a fabric on a shuttle loom, making a greige
fabric
having a 2x1 twill weave and a construction of 26 ends x 17 picks per cm (72
ends x 52 picks per inch), and a basis weight of 215 g/m2 (6.5 oz/yd2). The
greige
twill fabric is then scoured in hot water and is dried under low tension. The
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scoured fabric is then jet dyed using basic dye. The resulting fabric has a
basis
weight of 231 g/m2 (7 oz/yd2) and an LOI in excess of 28. Table 1 illustrates
properties of the resulting fabric. A "+" indicates superior properties to
those of
the control fabric, while the notation "0" indicates the performance of the
control
fabric or performance equivalent to the control fabric. A "0/+" means the
performance is slightly better than the control fabric.
Table 1
Property 100% PSA Example I
Nominal Basis Weight 7 7
(opsy)
Grab Test 0 +
Break Strength (Ibf)
W/F
Trap Tear 0 +
(Ibf) W/F
Taber Abrasion 0 +
(Cycles)CS-10/1000 g
TPP 0 0
(cal/cm2)
Vertical Flame 0 +
(in) W/F
Instrumented Thermal 0 +
Manikin Test (% of
body burn)
ARC rating(cal/cm2) 0 +
Example 2
The fabric of Example 1 is used as an outer shell fabric for a three-layer
composite fabric that also includes a moisture barrier and a thermal liner.
The
moisture barrier is Goretex having a basis weight of 0.7 oz/yd2 attached to a
nonwoven poly(metaphenylene isophthalamide)/poly(paraphenylene
terephthalamide) fiber blend substrate having a basis weight of 2.7 oz/yd2.
The
thermal liner is made from three 1.5 oz/yd2 spunlaced poly(metaphenylene
isophthalamide)/poly(paraphenylene terephthalamide) fiber sheets quilted to a
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3.2oz/yd2 poly(metaphenylene isophthalamide)staple fiber scrim. Protective
garments such as fireman turnout coats are then made from the composite
fabric.
Example 3
The fabric of Exarnple 1 is made into protective articles, including
garments, by cutting the fabric into fabric shapes per a pattern and sewing
the
shapes together to form a protective coverall for use as protective apparel in
industry. Likewise, the fabric is cut into fabric shapes and the shapes sewn
together to form a protective apparel combination comprising a protective
shirt
and a pair of protective pants. If desired, the fabric is cut and sewn to form
other
protective apparel components such as, coveralls, hoods, sleeves, and aprons.
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